The inducible enzyme cyanase catalyzes bicarbonate-dependent hydrolysis of cyanate. One set of objectives includes detailed elucidation of the mechanism and properties of this unique enzyme, identification of its biological role, and development of procedures for immobilizing the enzyme and utilizing the enzyme as a component of the extracorporeal system developed for treating sickle cell anemia with cyanate. Cyanate has been shown to be a specific inhibitor of carbamyl phosphate synthetase and several other amidotransferases. It apparently acts by carbamylating an essential SH group at the glutamine binding site. An objective is to obtain information about the properties of the interaction of cyanate at the glutamine binding site of several amidotransferases in order to establish in greater detail the mechanism(s) of the steps which are common to this group of enzymes, i.e., glutamine-binding and release of ammonia, ammonia transfer and reaction with an acceptor, and hydrolysis of the gamma-thioacyl intermediate. Specific information about the distance of ammonia transfer and the nature of the ammonia transfer site in carbamyl phosphate synthetase will be obtained by studying the interaction of various analogs of the amide group of glutamine with the enzyme and by measuring the exact spatial arrangement between the glutamine, other substrate, allosteric, and metal ion binding sites using EPR and NMR techniques. These and additional related studies are designed to provide information about the detailed mechanism(s) of this enzyme as a representative of other carbamyl phosphate synthetases and of the amidotransferases in general, particularly with respect to the ammonia transfer process.